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/usr/bin/tty [-l] [-s]
tty [ options ]
The tty utility writes to the standard output the name of the terminal that is open as standard input. The name that is used is equivalent to the string that would be returned by the ttyname(3C) function.
The ksh93 tty built-in writes the name of the terminal that is connected to standard input onto standard output. If the standard input is not a terminal, "not a tty" will be written to standard output.
The following options are supported:
-l
Prints the synchronous line number to which the user's terminal is connected, if it is on an active synchronous line.
-s
Inhibits printing of the terminal path name, allowing one to test just the exit status.
-l
--line-number
Write the synchronous line number of the terminal on a separate line following the terminal name line. If the standard input is not a synchronous terminal then "not on an active synchronous line" is written.
-s
--silent|quiet
Disable the terminal name line. Portable applications should use [[ -t 0 ]] instead.
See environ(5) for descriptions of the following environment variables that affect the execution of tty: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned:
0
Standard input is a terminal.
1
Standard input is not a terminal.
>1
An error occurred.
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| CSI | Enabled |
| Interface Stability | Committed |
| Standard | standards(5). |
isatty(3C), ttyname(3C), attributes(5), environ(5), standards(5)
not on an active synchronous line
The standard input is not a synchronous terminal and -l is specified.
not a tty
The standard input is not a terminal and -s is not specified.
The -s option is useful only if the exit status is wanted. It does not rely on the ability to form a valid path name. Portable applications should use test -t.